Electronic properties of interfaces between different sexithiophenes and gold

We present a photoemission study of the interface between sexithiophene and polycrystalline gold. Two different sexithiophenes have been investigated-alpha-6T and a derivative of alpha-6T(beta beta(')-DH6T) with additionally attached alkane chains at thiophene rings, which increases its solubility and allows application in solution-based processes. We find an interface dipole of 1.2 eV and we observe chemical interactions for both sexithiophenes. Special attention has been paid to the possible influence of the chemical modification on the electronic properties of the material itself and its influence on the interface properties with gold. In addition, we discuss the differences in the electronic structure of vacuum-sublimated and spin-coated films of beta beta(')-DH6T. We find indications for better ordered films applying the solution-based process and the spin-coating procedure leads to oxidation of the organic film. (c) 2005 American Institute of Physics.